Antenna Testing and Measurements

Planar Beam-forming Antenna Array for 60-GHz Broadband Communication

In wireless communication systems, high-performance antenna, microwave, and radio frequency design systems are essential to meet end-user requirements. As demand for these components increases, it's crucial to design optimized structures in a short amount of time with guaranteed best results. This has led to the need for a higher level of intelligence in the design process. Artificial intelligence (AI) techniques such as evolutionary algorithms (EAs), machine learning (ML), deep learning (DL), and knowledge representation have been widely used to find parameter values of antenna and microwave components, leading to optimized designs in minimum processing time and overcoming long processing times and poor results. This chapter focuses on the major AI methods in the area of antenna, microwave, and other radio frequency (RF) components, including phase shifters, intelligent reflective surfaces (RIS), waveguides, filters, stubs, etc. The chapter discusses different EAs and ML algorithms and their use in optimizing antenna and microwave designs.

This greatly expanded, co-authored, two-volume text provides a comprehensive introduction and explanation of both the theory and practice of modern antenna measurements, from their most basic postulates and assumptions, to the intricate details of their applications in various demanding modern measurement scenarios. Starting with an initial examination of the properties of antennas that allow them to enhance the free-space interaction of electronic systems, the authors then introduce direct far-field and indirect far-field forms of antenna measurements and their various implementations. Detailed descriptions are given of the direct far-field measurement technique CATR (Compact Antenna Test Ranges), Body-Centric measurements, and detailed developments of standard planar, cylindrical, spherical and non-canonical near-field techniques; and includes a through treatment of near-field range error budgets which are an indispensable part of antenna metrology. The books conclude with recent advances in measurement techniques such as aperture diagnostics, phase-less antenna metrology, error correction, and range multi-path suppression techniques. Extensive examples illustrate the concepts and techniques covered. This second edition is thoroughly expanded and now includes new chapters on near-field to far-field transforms from non-canonical surfaces, electromagnetic modelling of CATRs and near-field antenna measurement systems. In addition there is an expanded chapter on coordinate systems, polarization bases and antenna pattern plotting and new sections on more specialized topics such as 5G and Radome measurements.

Citation Muñoz Acevedo, Alfonso (2012). Contribution to the Analysis, Design and Assessment of Compact Antenna Test Ranges At Millimeter Wavelengths - Contribución al Análisis, Diseño y Caracterización de Sistemas de Medida de Antenas en Rango Compacto para Frecuencias Milimétricas. Thesis (Doctoral), E.T.S.I. Telecomunicación (UPM). https://doi.org/10.20868/UPM.thesis.11122.

At the lower VHF frequencies, the measurement of low gain antennas in a controlled anechoic environment including the space platform can be challenging. Often, the reflectivity of the anechoic environment is insufficient for a traditional single probe approach using near or far field techniques. This was the case in the testing of the 50-70MHz dipole antenna and cubesat satellite that is part of the ESA HERA-JUVENTAS mission. In this paper we discuss the measurement solution for the testing of this satellite in the ESA-HERTZ testing facility. The solution is based on an array of virtual probes generated by moving a physical single probe within the measurement setup. By a suitable optimization of the complex weight of the virtual array elements a plane wave and thus far field condition can be approximated in the satellite test volume while chamber wall reflections are minimized.

Engineering Work Station as a Tool for a Process Control Design and Implementation

Power extraction using a dielectric-loaded (DL) waveguide is a way to generate high-power radio frequency (RF) waves for future particle accelerators, especially for two-beam-acceleration. In a two-beam-acceleration scheme, a low-energy, high-current particle beam is passed through a deceleration section of waveguide (decelerator), where the power from the beam is partially transferred to trailing electromagnetic waves (wakefields); then with a properly designed RF output coupler, the power generated in the decelerator is extracted to an output waveguide, where finally the power can be transmitted and used to accelerate another usually high-energy low-current beam. The decelerator, together with the RF output coupler, is called a power extractor. At Argonne Wakefield Accelerator (AWA), we designed a 7.8GHz power extractor with a circular DL waveguide and tested it with single electron bunches and bunch trains. The output RF frequency (7.8GHz) is the sixth harmonic of the operational frequency (1.3GHz) of the electron gun and the linac at AWA. In single bunch excitation, a 1.7ns RF pulse with 30MW of power was generated by a single 66nC electron bunch passing through the decelerator. In subsequent experiments, by employing different splitting-recombining optics for the photoinjector laser, electron bunch trains were generated and thus longer RF pulses could be successfully generated and extracted. In 16-bunch experiments, 10ns and 22ns RF pulses have been generated and extracted; and in 4-bunch experiments, the maximum power generated was 44MW with 40MW extracted. A 26GHz DL power extractor has also been designed to test this technique in the millimeter-wave range. A power level of 148MW is expected to be generated by a bunch train with a bunch spacing of 769ps and bunch charges of 20nC each. The arrangement for the experiment is illustrated in a diagram. Higher-order-mode (HOM) power extraction has also been explored in a dual-frequency design. By using a bunch train with a bunch spacing of 769ps and bunch charges of 50nC each, 90.4MW and 8.68MW of extracted power levels are expected to be reached at 20.8GHz and 35.1GHz, respectively. In order to improve efficiency in HOM power extraction, a novel technique has been proposed to suppress unintended modes.

The application of conventional antenna phase measurement methods becomes increasingly difficult above 100 GHz. The main problems are the complexity of measurement set-ups and errors caused by the flexible cables or rotary joints needed in the system. To overcome these problems, a novel differential phase measurement method has been developed and used to measure phase centre positions and phase patterns of two corrugated horns at 105–115 GHz and 176–190 GHz. In spite of the simplicity, the differential phase method gives accurate results. Good agreement between themeasured values and theoretical values, calculated with the modal matching technique, were obtained.

Superconducting radio frequency niobium cavities are the building blocks of modern accelerators for scientific applications. Lower surface resistance, higher fields, and high operating temperatures advance the reach of the future accelerators for scientific discovery as well as potentially enabling cost-effective industrial solutions. We describe the design and performance of an Nb3Sn coating system that converts the inner surface of niobium cavities to an Nb3Sn film. The niobium surface, heated by radiation from the niobium retort, is exposed to Sn and SnCl2 vapor during the heat cycle, which results in about 2 μm Nb3Sn film on the niobium surface. Film composition and structure as well as radio frequency properties with 1-cell R&D cavities and 5-cell practical accelerator cavities are presented.

Antenna measurements are usually categorized by the location of the measurement facility, either indoor or outdoor. This chapter introduces the antenna parameters that need to be validated in an antenna test facility. The input impedance of the antenna is an important measure that determines how much of the power which is transported along the transmission line is actually radiated by the antenna. Many commercial mmWave antenna test facilities have bulky and metallic moving parts. However, the design of the mmWave anechoic chamber has a confined space where the antenna‐under‐test is positioned such that moving and supporting objects have a negligible effect on the measured radiation characteristics. In over‐the‐air testing, a communication link is setup and some form of information is exchanged between the antenna system under test and the tester, for example by means of transferring data packets in order to determine the bit error rate and the packet error rate.

A practical optical rotary joint and optical links were prepared for an antenna measurement. The rotational variation loss of the optical rotary joint depends on the mechanical misalignments. To achieve 0.2 dB or less rotational variation loss, we proposed a new structure that has a noncontact interface using two size-mismatched fibers without a lens. The optical links are made of a distributed-feedback laser diode, a PIN-photodetector, and single-mode fiber jumper cords. The proposed rotary joint has very low rotational variation loss. The optical links are sufficiently stable to be applied to the antenna measurement. We verified that the rotary joint and optical links can be adopted in RF antenna test applications.

This paper discusses the antenna measurement techniques and antenna test facilities developed over the last decades at a number of enterprises in Ukraine. These facilities include far-field, near-field and compact ranges and automatic test systems. Some of these ranges are described more detailed. The significant progress in obtaining improved measurement accuracy is also discussed here. The characteristics of anechoic chambers built in Ukraine are briefly discussed.

Antenna metrology at the Antenna Test Laboratories is extensive and state-of-the-art in many areas. The facilities include two 30 foot rectangular chambers, a 75 foot tapered chamber, several outdoor ranges up to 1100 feet, a large compact range with a 12 foot quiet zone and the Near Field Measurement Laboratory (NFML). Antenna measurements have been performed in these facilities from 100 MHz to 40 GHz. The NFML was built in 1978 as the premier facility for performing extremely accurate high gain antenna metrology. The NFML is the largest near field scanner in existence, and applied near field techniques on a massive scale shortly after their initial development. The scanner is capable of characterizing antenna apertures up to 16.5 meters in diameter (54 feet) with the maximum physical scan size of 23.7/spl times/23.7 meters (78/spl times/78 feet). As antenna technology evolved since this facility was built it has begun to standardize on many of the features used to make this facility the reliable, accurate instrument it still is today. This paper discusses the power of near-field metrology, industry trends, and instrumentation for near-field measurement facilities of the future.

This paper presents results of the research project: "Characterization of the radio frequency (RF) properties of LDS-MID" where RF parameters of laser direct structureable (LDS) molded interconnect device (MID) materials were investigated. First of all the most important material parameters influencing the RF performance of a device are introduced. In the next section the broadband characterization of the metallization and material properties using a coplanar waveguide (CPW) is described. For a selected LDS material the conduction losses due to different metallization compositions are discussed in detail.

In this work, the effect of high-energy proton irradiation on the radiofrequency (RF) properties of silicon-on-insulator (SOI) substrates is investigated. The localized backside etching (LBE) structure is introduced for RF properties improvement and proton irradiation hardening. It is observed that after the 50 MeV proton irradiation with a fluence of 1 × 1012 p cm−2, the attenuation, crosstalk, and relative permittivity significantly decrease for conventional SOI substrates. In contrast, LBE substrates are less sensitive to proton irradiation and simultaneously exhibit better RF performance. The enhancement of the LBE structure on irradiation tolerance is qualitatively characterized by the equivalent circuit model parameter extraction.